Convertible ladder



Aug. 13, 1963 H. HOPFELD 3,100,552

CONVERTIBLE LADDER Filed Feb. 21, 1961 2 Sheets-Sheet 1 Iz'g 3.

INVENTOR. HE/W? Y HOPFELD ATTORNEY Aug. 13, 1963 H. HOPFELD 3,100,552

CONVERTIBLE LADDER Filed Feb. 21, 1961 2 Sheets-Sheet 2 INVENTOR. HENRY HOPFELD ATTORNEY United States Patent 2,100,552 CQNVERTEBLE LADDER Henry Hopteld, 732 A St, San Rafael, Calif. Filed Feb. 21, 1961, her. No. 9d,6%

2 Claims. ((11. 1$222) This invention relates to a convertibleladder.

The primary feature of this invention is that a ladder is provided which can be converted quickly into various types as needed, for instance, into a step ladder or used as two straight ladders, or as an extension ladder; this convertibility is accomplished by the coaction of a joint or joining bracket and guides coacting with suitable abutments on the respective ladders and other devices as shown to quickly convert the two ladders in the various arrangements as needed.

I. am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, as well as in the details of the construction thereof without departing from the scope of the present invention as set forth in the following specification, and as defined in the following claims; hence I do not limit my invention to the exact arrangements and combinations of the said device and parts as described in the said specification, nor do I confine myself to the exact details of the construction of the said parts as illustrated in the accompanying drawings.

With the foregoing and other objects in view, which will be made manifest in the following detailed description, reference is had to the accompanying drawings for the illustrative embodiment of the invention, wherein:

FIG. 1 is a perspective view partly in section showing the two ladders combined into a stepladderm FIG. 2 is a fragmental view of the top portion of the stepladd er with the coacting bracket and abutment on the respective ladders.

FIG. 3 is a fragmental sectional view of the top por tion of the ladders showing the manner of disengagement of the ladders from the stepladder position into straight ladders.

PEG. 4 is a view showing the ladders converted into on extension ladders.

FIG. 5 is a fragmental edge View of the coacting brackets and 'abutments on the tops of the ladders.

FIG. 6 is a fragmental sectional view the section being taken approximately on the lines 6-6 of the FIG. 2.

FIG. 7 is a detail perspective view of the top bracket viewing from the side of the guide.

FIG. 8 is another perspective view of the top bracket viewing from the base plate, the rail being shown in broken lines.

In carrying out my invention 1 make use of a pair of straight ladders A and B at the upper ends of which are coacting means C adapted to hold the two ladders together at a suitable angle for forming a usual stepladder. The coacting means C are releasable by bringing the step ladders A and B toward a parallel position and the coacting elements on the top of the ladder A are adapted to function .as guides and retainers for the upper ladder B when the two stepla-dders are used as extension ladders. The connecting means C is also adapted for permitting quick disengagement of the tops of the ladders for separation into two straight ladders. Suitable means are provided for resting the lower end of the ladder B on the rungs of the ladder A when the same are used as an extension ladder as shown in FIG. 4.

Each straight ladder A and B has a pair of parallel rails 1 connected by the usual rungs 2. The straight ladder B, used as an extension, is of such width that it slidably fits between the rails 1 of the lower ladder A.

The coacting connecting means C includes a bracket 3 on the top of each rail 1 of the lower ladder A. Each bracket 3 includes a base plate 4 provided with suitable holes 6 to accommodate securing elements such as rivets 55 or the like to mount it on the inner face of the rail 1. The base plate 4 projects beyond an edge of the adjacent rail 1 and its projecting end is formed into a retainer guide 7 which conforms substantially to the contour of the rail 1 of the upper ladder B. In the present form the retainer guide 7 is generally U-shaped, the open end of the U-shape being offset inwardly of the adjacent rail of the lower ladder A. The lower edge of the closed end of the U-shaped retainer guide or socket 7 is provided with an outwardly flaring lip 8, away from the adjacent rail of the lower ladder, generally at an angle corresponding to the angle of incline of the adjacent rail 1 of the upper ladder B in the stepladder position.

At the lower inner corner of the base plate 4, is a rest flange 9 at an angle generally parallel with the angle of the lip 8 so that the face of the rest flange 9 is spaced from the lip 8 at such a distance that the rail 1 of the upper ladder B in the stepladder position engages the inside of the parallel lip 8 and rests on the rest flange 9 as shown in FIG. 2. The rest flange 4 has a base 1%? which partly overlaps the base plate 4 and is suitably attached to the rail 1 and to the base plate 4. On the top edge of the base plate 4 is a top plate 11 corresponding to the contour of the top of the adjacent rail 1 of the lower ladder A. This top plate 11 has suitable holes 12 to accommodate screws 13 to secure the top plate 11 onto the top of the adjacent rail 1.

Near the top of each rail of the upper ladder B are provided a pair of dogs 14 and 15 olfset longitudinally on opposite edges 16 of the rail 1 of the upper ladder B so that the upper dog 14 is nearer to the upper end of the rail 1 than the lower dog 15'. The spacing between the abutment ends 17 of the respective dogs 14 and 15 is substantially the same as the distance between the upper edge 18 of the rest flange 9 and the lower edge of the lip 8 so as to abut against said edges in the stepladder' position of the ladders A and B as shown in FIG. 2.

In this illustration the top of the ladder B is covered by a generally U-shaped recessed cover plate 19 suitably secured in place.

The hook means for supporting the upper ladder B as an extension, in the present illustration, are a pair of hooks 21, one of which is suitably secured to the inner face of each rail 1 of the upper ladder B at the lowest rung 2 of said upper ladder B.

In operation the two ladders A and B can be quickly assembled to form a stepladder by inserting the top ends of the rails 1 of the upper ladder B into the guide or socket 7 in a position substantially as shown in FIG. 3 so that the upper dog 14 passes through the guide 7 and the lower dog 15 is in registry with the lower end of the lip 8. The dogs 14 and 15 are of such height that total width of each rail 1 and the height of either dog is less than the space between the lower edge of the rest flange 9 and the lip 8 so that the rail with the dogs can be passed therethrough where the upper rail 1 is nearly parallel with the lower ladder A. Then the ladders are tilted to about the incline shown in FIG. 2, in which position the upper edge 16 of each rail 1 of the upper ladder B abuts against the lip 8 and the lower edge of the same rail 1 rests upon the rest flange 9. In this position the upper dog 14 bears against the upper edge 18 of the rest flange 9 and the lower dog 15 bears against the lower edge of the lip 8. As weight is placed upon the stepladder from either side, it will tend to push the ladders apart and the more weight hears upon the step ladder the firmer will be the locking engagement between the edges of the nails 1 of the upper ladder and the lip 8 and the rest flange 9 respectively. and the firmer will 'be the engagement by the respective dogs 14 and 15.

For separating the ladders, the same are moved together to a less acute angle so that the rails of the upper ladder B assume substantially the position shown in FIG. 3, then the ladder A may be moved upwardly relatively to the ladder B and as it is further moved toward the panallel position, it will permit the upper dog 14 to pass through the space between the lip 8 and the rest flange 9, thus severing the connecting means between the ladders and resulting in two straight ladders.

In order to use the same combination as an extension ladder, the upper and lower ladder A and B are placed in the position shown in FIG. 3, but in this instance the upper ladder B is pushed upwardly and in'the position shown in FIG. 3, the lower dog will pass through the guide 7 upwardly and as the upper ladder B assumes the posiiton parallel and overlapping with respect to the lower ladderA, the rails 1 of the upper ladder B nest in the respective channel guides 7 as shown in FIG. 4, and are allowed to be slid parallel into desired extended position in which position the respective hooks 21 can be placed over the adjacent rung 2 of the lower ladder A, as shown in FIG. 4, to hold the two ladders in extended position so that the upper ladder is supported by the hooks and by the guides or sockets 7.

The adaptability of two ladders into various types of combinations without the use of any other attachments is of great advantage, it in effect provides four ladders in one with quick adjustments, assemblies and attachments to accomplish the desired result.

I claim:

1. In a convertible ladder structure (a) a lower individual ladder,

(b) an upper individual ladder,

(c) the rails of the upper ladder sl-idably fitting between and along the respective rails of the lower ladder,

(d) and separate connecting means on said individual ladders to connect said ladders selectively in stepladder attitude and extension-ladder attitude comprising (e) a bracket on the top of each rail of said lowerladder, each bracket including (1) a base plate secured to a face of the adjacent rail,

(g) an end of said bracket projecting toward the upper ladder and beyond the edge of the adjacent rail and being for-med into a retainer guide conforming to the l contour of the adjacent rail of the upper ladder so as to embrace the latter in said extension-ladder attitude, (lz) a rest flange extended from said base plate spaced from said guide atan incline corresponding to the relative incline of said upper ladder in said stepladder attitude and at such a distance from the lower edge of said retainer guide that the upper edge of the rail of said upper ladder engages the lower edge of said retainer guide when the lower edge of said rail of said upper ladder rests on said rest flange, (i) a first abutment projecting from the lower edge of the rail of said upper ladder,

(j) and a second abutment projecting from the upper edge of the rail of said upper ladder,

(k) said abutments being spaced longitudinally of said rail of said upper ladder at a distance equal to the distance between the upper edge of said rest flange and the lower edge of said retainer guide so as' to fix said upper rail against longitudinal movement relatively to said retainer guide in said step-ladder attitude,

(I) the thickness of each abutment together with the width of its rail being less than the distance between the lower edge of said inclined rest flange and the lower edge of said guide to that the upper end portion of said rail of said upper ladder is movable between said guide and said flange in either direction.

respectively for extension and separation of said ladders when said ladders are in substantially parallel position and the rails of said upper ladder ride on the rungs of the lower ladder,

(m) and releasable means to hold said ladders together in selected extended relation.

2. A convertible ladder structure as define-d in claim 1,

and

(11) an outwardly flaring lip on the lower edge of said guide parallel with said inclined rest flange for engaging the upper edge of said rail of said upper la der in said guide in step-ladder attitude.

References Cited in the file of this patent UNITED STATES PATENTS 675,744 Lewis June 4, 1901 766,246 Hartzler Aug. 2, 1904 1,579,701 Givens Apr. 6, 1926 1,996,133 White Apr. 2, 1935 2,133,003 Webster Oct. 11, 1938 

1. IN A CONVERTIBLE LADDER STRUCTURE (A) A LOWER INDIVIDUAL LADDER, (B) AN UPPER INDIVIDUAL LADDER, (C) THE RAILS OF THE UPPER LADDER SLIDABLY FITTING BETWEEN AND ALONG THE RESPECTIVE RAILS OF THE LOWER LADDER, (D) AND SEPARATE CONNECTING MENS ON SAID INDIVIDUAL LADDERS TO CONNECT SAID LADDERS SELECTIVELY IN STEPLADDER ATTITUDE AND EXTENSION-LADDER ATTITUDE COMPRISING (E) A BRACKET ON THE TOP OF EACH RAIL OF SAID LOWER LADDER, EACH BRACKET INCLUDING (F) A BASE PLATE SECURED TO A FACE OF THE ADJACENT RAIL, (G) AN END OF SAID BRACKET PROJECTING TOWARD THE UPPER LADDER AND BEYOND THE EDGE OF THE ADJACENT RAIL AND BEING FORMED INTO A RETAINER GUIDE CONFORMING TO THE CONTOUR OF THE ADJACENT RAIL OF THE UPPER LADDER SO AS TO EMBRACE THE LATTER IN SAID EXTENSION-LADDER ATTITUDE, (H) A REST FLANGE EXTENDED FROM SAID BASE PLATE SPACED FROM SAID GUIDE AT AN INCLINE CORRESPONDING TO THE RELATIVE INCLINE OF SAID UPPER LADDER IN SAID STEPLADDER ATTITUDE AND AT SUCH A DISTANCE FROM THE LOWER EDGE OF SAID RETAINER GUIDE THAT THE UPPER EDGE OF THE RAIL OF SAID UPPER LADDER ENGAGES THE LOWER EDGE OF SAID RETAINER GUIDE WHEN THE LOWER EDGE OF SAID RAIL OF SAID UPPER LADDER RESTS ON SAID REST FLANGE, (I) A FIRST ABUTMENT PROJECTING FROM THE LOWER EDGE OF THE RAIL OF SAID UPPER LADDER, (J) AND A SECOND ABUTMENT PROJECTING FROM THE UPPER EDGE OF THE RAIL OF SAID UPPER LADDER, (K) SAID ABUTMENTS BEING SPACED LONGITUDINALLY OF SAID RAIL OF SAID UPPER LADDER AT A DISTANCE EQUAL TO THE DISTANCE BETWEEN THE UPPER EDGE OF SAID REST FLANGE AND THE LOWER EDGE OF SAID RETAINER GUIDE SO AS TO FIX SAID UPPER RAIL AGAINST LONGITUDINAL MOVEMENT RELATIVELY TO SAID RETAINER GUIDE IN SAID STEP-LADDER ATTITUDE, (L) THE THICKNESS OF EACH ABUTMENT TOGETHER WITH THE WIDTH OF ITS RAIL BEING LESS THAN THE DISTANCE BETWEEN THE LOWER EDGE OF SAID INCLINED REST FLANGE AND THE LOWER EDGE OF SAID GUIDE TO THAT THE UPPER END PORTION OF SAID RAIL OF SAID UPPER LADDER IS MOVABLE BETWEEN SAID GUIDE AND SAID FLANGE IN EITHER DIRECTION RESPECTIVELY FOR EXTENSION AND SEPARATION OF SAID LADDERS WHEN SAID LADDERS ARE IN SUBSTANTIALLY PARALLEL POSITION AND THE RAILS OF SAID UPPER LADDER RIDE ON THE RUNGS OF THE LOWER LADDER, (M) AND RELEASABLE MEANS TO HOLD SAID LADDERS TOGETHER IN SELECTED EXTENDED RELATION. 